Purpose of Review This narrative review provides an update of our knowledge on the relation between heavy cannabis use and cannabis use disorder (CUD) and the brain based on (f)MRI studies conducted in the past 5 years.

Recent Findings Heavy cannabis use and CUD are associated with structural brain changes—particularly volume—as well as altered resting-state functional connectivity (RSFC) in several networks and regions. Task-based fMRI studies reveal altered activity and connectivity in cannabis users compared to controls, but consistency of the results is domain dependent. Heaviness of use, CUD status, age, sex, and tobacco co-use are important potential moderators of the effects of cannabis on the brain.

Summary Heavy cannabis use and CUD are associated with differences in brain structure and function, but causality remains unclear, and long-term effects following abstinence require further investigation. Considering moderators of the effects of cannabis on the brain is crucial to further assess individual differences in the impact of cannabis use.